lavf/utils: use stream PTS wrap-around values as default if smaller o…

…r much larger than default

Seems to fix mistaken cases of discontinuity handling in MPEG-TS files
when streams get added in.

Additional changes to patch from its original state by Jan Ekström.

libavformat/utils.c

@@ -810,8 +810,46 @@ static int update_wrap_reference(AVFormatContext *s, AVStream *st, int stream_in
         while (program) {
             if (program->pts_wrap_reference != pts_wrap_reference) {
                 for (i = 0; i<program->nb_stream_indexes; i++) {
-                    s->streams[program->stream_index[i]]->pts_wrap_reference = pts_wrap_reference;
-                    s->streams[program->stream_index[i]]->pts_wrap_behavior = pts_wrap_behavior;
+                    int64_t *stream_pts_wrap_reference = &(s->streams[program->stream_index[i]]->pts_wrap_reference);
+                    int     *stream_pts_wrap_behavior  = &(s->streams[program->stream_index[i]]->pts_wrap_behavior);
+
+                    if (*stream_pts_wrap_reference != AV_NOPTS_VALUE &&
+                        (*stream_pts_wrap_reference - pts_wrap_reference > 1ULL << (st->pts_wrap_bits - 3) ||
+                         *stream_pts_wrap_reference < pts_wrap_reference)) {
+                        /*
+                         * Utilize the current stream's wrap-around reference
+                         * as the default reference if this stream's
+                         * wrap-around reference is already not NOPTS,
+                         * and either:
+                         *   1) the stream's wrap-around reference is
+                         *      after the default program's reference
+                         *      by at least the most significant bit's value
+                         *      of (pts_wrap_bits - 3).
+                         *   2) the stream's wrap-around reference is
+                         *      before the default one.
+                         */
+                        av_log(s, AV_LOG_VERBOSE,
+                               "Updating default PTS wrap reference "
+                               "%"PRId64" and PTS wrap behavior %d to "
+                               "stream PTS wrap reference %"PRId64" and "
+                               "PTS wrap behavior %d (program=%d, stream=%d, "
+                               "stream_id=%d)\n", pts_wrap_reference,
+                               pts_wrap_behavior,
+                               *stream_pts_wrap_reference,
+                               *stream_pts_wrap_behavior,
+                               program->id, program->stream_index[i],
+                               s->streams[program->stream_index[i]]->id);
+
+                        pts_wrap_reference = *stream_pts_wrap_reference;
+                        pts_wrap_behavior  = *stream_pts_wrap_behavior;
+                    } else {
+                        /*
+                         * otherwise just utilize the default program's
+                         * wrap-around reference for this stream.
+                         */
+                        *stream_pts_wrap_reference = pts_wrap_reference;
+                        *stream_pts_wrap_behavior  = pts_wrap_behavior;
+                    }
                 }
 
                 program->pts_wrap_reference = pts_wrap_reference;